Fresh evidence that a senior government press officer was closely involved in drawing up the government's discredited Iraq weapons dossier, despite official denials, was revealed yesterday.

A document the Foreign Office tried to suppress shows that John Williams, its director of communications at the time, had access to secret intelligence as he prepared an early draft in 2002.

The document suggests that Williams, a former Sunday Mirror political editor, used the same sources as the Joint Intelligence Committee, chaired by Sir John Scarlett, which produced the government's final dossier. Though there are striking similarities, Williams's draft does not contain the claim that Iraq could launch a chemical warfare weapon in 45 minutes - a claim central to the prime minister's case for war.

The 45-minute claim was made later, and subsequently withdrawn.

The FO fought to suppress the Williams draft. The information tribunal ordered its release, observing that it may have played a bigger role in influencing the dossier than previously supposed.

Yesterday, in a written statement to MPs, David Miliband, the foreign secretary, said the Williams document was not commissioned as part of the drafting process and was not used as the basis for the dossier the government published.

The Williams document was drawn up in early September 2002. While officials distanced Williams from the drafting during the Hutton inquiry into the death of the government's weapons expert, David Kelly, a number of references were made to it there.

Scarlett referred at the inquiry to "drafting" by Williams, albeit on Williams's own initiative, and of "considerable help" Williams had given him. Williams attended Cabinet Office meetings on the weapons dossier, the inquiry was told.

The draft, released yesterday, contains the first known references to a number of government claims. It refers to Iraq having missiles capable of "threatening Nato" - though Williams adds a question mark after mentioning Greece and Turkey.

It states that there was "compelling evidence that Iraq has sought the supply of significant quantities of uranium from Africa" - a claim which turned out to be untrue.

These claims were reflected in the government's final dossier, published in late September 2002. This stated that Iraq was developing missiles "capable of reaching the UK sovereign base areas in Cyprus and Nato members (Greece and Turkey)". And the final dossier said there was "intelligence that Iraq has sought the supply of significant quantities of uranium in Africa".

There is evidence of some of Williams's claims being questioned. He begins his draft with the words: "Iraq presents a uniquely dangerous threat to the world. No other country has twice launched wars of aggression against neighbours." In a margin someone has written: "Germany? US: Cuba, Guatemala, Mexico."

William Hague, shadow foreign secretary, said the Williams document was "further evidence that spin doctors, not intelligence analysts, were leading from the first in deciding what the British people were told about Iraq's weapons of mass destruction". He added: "What is really needed is [a] full-scale privy council inquiry into the origins and conduct of the Iraq war."